Securement system using loose keys for independent storage tanks

ABSTRACT

An arrangement for securing independent storage tanks or containers in a tanker or other vehicle of transportation for transporting cargoes below or above ambient temperature wherein the arrangement comprises a system of key-keyway-bearer combinations removed from the neutral axis of the container, preferably located at the top and the bottom of the storage tank and utilizing loose keys, or in other words, keys that are detached from the surrounding keyway-bearer structure.

Walter C. Cowles [72] Inventor 3,071,094 1/1963 Leroux 220/15 XStamford, Conn. 3,270,700 9/1966 Kohn et al. 220/9 LG [21] App1.No.15,040 3,319,431 5/1967 Clarke et al. 62/45 [22] Filed Feb. 27, 1970FOREIGN PATENTS [45] Patented Oct. 12,1971 1 293 275 4/1962 F rance 220/[73] Assgnee Research and Eng'neenng 683,855 12/1952 Great Britain220/15 Primary Examiner-Joseph R. Leclair 54 SECUREMENT SYSTEM USINGLOOSE KEYS FOR Assistant Examinerlames Garrett INDEPENDENT STORAGE TANKSArtomeys-Manahan and Wright and F. Donald Paris 12 Claims, 6 DrawingFigs.

[52] 11.5. CI 220/15, A STRACT; A n ment for securing independent 114/74A storage tanks or containers in a tanker or other vehicle of [51]1nt.Cl 865d /00 transportation for transporting cargoes below or aboveam- Field of Search 220/9 LG, biem temperature h i the anangememcomprises a 15; 1 14/74 A; 62/45 system of key-keyway-bearercombinations removed from the neutral axis ofthe container, preferablylocated at the top and [56] References Cited the bottom of the storagetank and utilizing loose keys, or in UNITED STATES PATENTS other words,keys that are detached from the surrounding 3,064,612 1 1/1962 Gardneret a1 220/15 X keyway-bearer structure.

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a 3/ J0 112 302/ 45 U 2 Jr J Al FI 1 j T- 17 56 23'" f7 25" 44 V7PATENTED um 1 2mm 1 1 2 333 sum 20F 2 45 AL URINE 14 I "Q INVENTORWALTER C. COWL S 4/ 38 /v ATTORNEY SECUWEMENT fiifSTlEll/ll USING LGGSIEliilEiiS ll tOllt llNDlEPlENlDlENT STORAGE TANKS BACKGROUND OF THElNVENTlON The present invention relates in the broadest sense to thestorage and transportation of liquids such as liquefied natural gas,hereinafter referred to as LNG, at extremely low tempera tures wellbelow ambient temperature and at essentially atmospheric pressure. Moreparticularly, the present invention is concerned with a novel andimproved system for securing storage tanks carrying LNG or the like inlarge quantities within a moving vehicle such as a tanker and whereinthe system uses loose keys.

it is well know in the art that the transportation of gasses, such asnatural gas and the like, to locations remote from its source of originmay best and most efficiently be accomplished by reducing the volume ofthe gas through its conver sion into the liquid state. Such a conversionenables the storage volume requirements to be greatly reduced (e.g.,approximately sixhundredfold for a given quantity of methane gas and, aswill be appreciated by those skilled in the art, enables the mostefficient and orderly transfer of the gas to the remote area.

in order to transfer LNG in a practical and economically feasible mannerin relatively large volumes, it is necessary to store the liquefiednatural gas at approximately atmospheric pressure, since largecontainers built to withstand superatmospheric pressures would beimpractical, if not impossible, to construct for use on seagoing tankersor vessels and the like. The LNG now is kept in storage containershaving exceptionally large capacities and these containers whentransported by tanker are confined within the cargo hold space of thetanker. To prevent heat losses which would lead to excessivevolatilization of the stored liquified gas, it is essential to provideproper thermal insulation for the containers. Also, the containers mustbe of sufficient strength to withstand the internal stresses that may beinduced therein by large temperature gradients through the walls of thecontainer. in using con tainers having such large capacity in a movingvehicle, it is desirable to maintain absolute control of the movementsof the containers so as to avoid bumping or shifting movements thereofin response to the erratic movements of the transportation vehicle, suchas the pitch and roll movements of a seagoing tanker. The problem ofproperly securing the containers in the cargo hold space providedtherefor in the tanker further is increased by the need to compensatefor movement of the storage containers caused by the expansion orcontraction thereof that comes about due to the storage of thecontainers at a temperature well below that of ambient temperature. Thischange in temperature naturally will result in con siderable contractionin the dimensions of the containers when filled with a material such asliquefied gas or the like, and in a corresponding expansion when thecontainers are emptied and allowed to rise in temperature. Heretofore,the solution to the problem of properly securing the containers in thetankers cargo hold space has been the use of key-keyway systemsemploying keys formed integral with the tanker-s hull.

The prior art securement arrangements have been found to beunsatisfactory in many respects. Frequently, prior art securernentsystems for mounting containers in a tanker have relied upon verticallydisposed key-keyway arrangements. These prior art arrangements have notonly been relatively complex and costly to construct, but have beenineffective in providing an equalized distribution of stressconcentrations along the entire key-keyway structure. This is becausethe key-keyway is located at the vertical center of the containersidewalls and therefore, the stress is concentrated at one or twolocalized points which normally are at either end of the key. Thus, thepossibility of local failure where greater stress concentrations occuris greatly increased. Since these arrangements are structurallyinefficient the consequence is a substantial increase in the cost. Otherprior art systems have used top and/or bottom key-keyway arrangementswherein the key is formed integral with the tankers bull or thecontainer. Since the key and key-way constructions are formed as anintegral part of the container or the tankers hull, the construction ofthe container is substantially more complicated and, also, it issubstantially more difficult to inspect and repair the keys and thekeyways. Further, the keys do not always properly mate with the keywaysthereby requiring further modification at the site of the tanker orother vehicle of transportation.

SUMMARY OF THE INVENTION The present invention overcomes both these andother prior art deficiencies by providing a novel and improvedarrangement for securing independent storage tanks or containers inposition in a tanker or vehicle of transportation, while allowing forcontraction or expansion of the container caused by the loading of thecargoes, such as LNG, at lower than ambient temperature. The systemcomprises essentially an arrangement of keys, keyways and bearersupports located at the bottom of the container in directionscorresponding to and along the longitudinal and transverse centerlinesof the tank. Specifically, a lower keyway and container support pedestalare secured to the inner bottom wall of the tankers hull. A matchingkeyway and container bearing member are secured to the underside of thecontainer. A. loose key, preferably made of fabricated steel, is fittedinto the channel formed between the keyways to secure the container fromundesirable lateral and longitudinal movement relative to the ship. Thecontainers bottom or lower keyways are designed so that its width iswider than they key at ambient temperature by an amount carefullycalculated to correspond to the amount of thermal contraction thatoccurs when the container is cooled to the temperature of the cargo.Thus, at operating temperature the key will fit neatly in the keyway.The containers may be further supported by additional bearer members andsupport pedestals located near the outboard sides of the container. Tofurther secure the containers against any upsetting force that mayresult from the motion of the transportation vehicle, there is provideda second key and keyway system located at the top of the containerextending in a direction on the longitudinal centerline thereof. As withthe lower container keyways, the keyways secured to the top of thecontainer are constructed to suit the dimension of the key when thecontainer is cold. Matching keyways are secured to the underside of thedeck and these upper keyways are fitted only in alternate bays formedbetween adjacent deck girders. The keys are designed to be shorter thanthe distance between the adjacent girders to facilitate their insertioninto the keyway. Thus, installation of the containers, deck structureand keyways can be accomplished prior to the final fitting and insertionof the keys. The container securement of the present invention is moreeffective than that proposed by the prior art, since forces andtherefore stress concentrations are equally distributed along thecontainer, bearing areas are substantially reduced, and the key supportstructure can be less extensive than required heretofore. The use of acommon structure for slidably mounting the keys and providing bearersupport substantially reduces the construction costs and minimizesthermal losses. A significant feature of the present invention comprisesthe use of loose keys which permits the keys and keyways to be machinefinished under workshop conditions prior to final installation. Also,the use of loose keys permits the withdrawal of the keys for inspectionand repair if required. By virtue of the fact that the presentarrangement provides for equal distribution of forces, the stressconcentrations are evenly distributed on the container and consequentlythe possibilities of failure associated therewith are substantiallyreduced. Further, the use of loose keys as compared to integral formedmale tenons simplifies and expedites construction of the storagecontainers.

Accordingly, it is a primary object of the present invention to providea novel and improved system for securing storage containers in atransportation vehicle, such as a tanker, which is low in cost,economical in construction, and reliable in operation.

Another object of this invention is to provide a novel and improvedsystem for securing independent storage container and which uses loosekeys.

A further object of this invention is to provide a novel and improvedkey-keyway system for securing a storage container in a cargo hold of avehicle and wherein there is equal distribution of stress concentrationsalong the container.

Having in mind the above and other objects that will be evident from anunderstanding of this disclosure, the invention comprises the devices,combinations construction, arrangements of parts as illustrated in thepresently preferred embodiment of the invention which is hereinafter setforth in such detail as to enable those skilled in the art readily tounderstand the function, operation, construction, and advantages of itwhen read in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a transverse cross-sectionalview taken substantially along the line 1-1 in FIG. 2 ofa tanker inwhich the new and improved system for mounting a storage containeraccording to the principles of the present invention has been installed;

FIG. 2 is a bottom plan view taken substantially along the line 22 inFIG. 1 of the storage container partially broken away;

FIG. 3 is a top plan view taken substantially along the line 33 in FIG.1 illustrating a portion of the top of the storage container embodyingthe features of the present invention;

FIG. 4 is a enlarged cross-sectional view taken substantially along theline 44 in FIG. 3 showing details of construction of a top key-keywayarrangement constructed in accordance with the present invention;

FIG. 5 is an enlarged cross-sectional view taken substantially on theline 5-5 in FIG. 2 illustrating details of construction of a bottomkey-keyway-bearer arrangement constructed in accordance with the presentinvention; and

FIG. 6 is an exploded perspective view illustrating a bottomkey-keyway-bearer arrangement embodying the principles of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention isdisclosed in combination with a cryogenic storage container for storingliquefied natural gas (LNG) or the like at atmospheric pressure, such asdisclosed in the US. Pat. ofClarke et al., No. 3,319,431, issued May 16,I967, and assigned to the assignee of the present invention, wherein thecontainer is fully disclosed and to which reference may be had for amore complete understanding thereof.

Referring now to the drawings, there is illustrated in FIG. 1 a storagecontainer 10 which is installed in a double-hulled tanker 11 (although asingle-hulled tanker may be suitable) having an outer hull 12 and aninner hull 13 which are maintained in separated spaced relationship bystructural members 14 and which defines a cargo hold space I5. Thecontainer 10 includes an inner tank 16 which constitutes a primarybarrier having the general shape of the cargo hold 15 and which isfabricated from aluminum, stainless steel, high nickel steel, aluminumalloy or a like material which is capable of withstanding the thermalstresses induced by the cryogenic cargoes. The inner tank 16 is enclosedby a similarly shaped and designed outer tank 17 which constitutes anouter or secondary barrier and also, as with the inner tank 16, isfabricated from a material such as aluminum or the like which is notdeleteriously affected by the extremely cold temperatures of thecryogenic cargoes. The tanks 16 and 17 are maintained in space relationby means of rigid spacing members 18 secured therebetween.

The double-walled tank or storage container 10 is provided about itsouter surface with an exterior layer of thermal insulation 19. It willbe understood by those skilled in the art that for purposes of thepresent invention the layer of insulation I0 may be located otherwisethan as illustrated. For example, it may be situated along the innerhull of the tanker ll. Briefly referring to the internal construction ofthe tank 10, there is illustrated as impervious longitudinal bulkhead 20that is effective to prevent sloshing of the LNG cargo from side-to-sidewithin the tank. The tank also includes horizontal flats 21 and 22 whichinclude a plurality of apertures 23 and 24, respectively, to permitdrainage and circulation.

As shown in FIG. 1, the tank 10 properly is secured in position withinthe cargo hold 15 of the double-hullcd tanker 11 by means of a bottomkey-keyway-bearer system generally designated 25 and a top key-keywaysystem generally designated 26. Also, to further provide support for thetank 10 there is provided at the tank bottom a plurality ofbearer/support arrangements generally designated 27 situated near theoutboard sides of the tank. At the bottom of the tank 10 the system 25comprises a plurality of keywaybearer means 28, one pair beinglongitudinally disposed and a second pair being transversely orlaterally disposed keyways, each of the pairs located along linescorresponding to the respective centerlines of the tank 10 as bestillustrated in FIG. 2. Since each of these keyway-bearer means 28 areidentical in their construction and arrangement, only one need bedescribed for purposes of understanding the present invention. Thekeyway-bearer 28 comprises a lower keyway or elongated channel 29secured to the underside of the tank 10. See FIGS. 2 and 5. The keyway29 is formed by a pair of laterally spaced keyway vertical bearingmembers 30, which are made of balsa wood, fir or other suitablematerial, which extend the length of the members 30 and are locatedadjacent to tank bottom, and that properly are secured in place by meansof support brackets 31 which are suitably fastened at one end to thebottom of tank 10 and at the other end to the vertical bearing member30. These brackets 31 comprise the same material as that for the tankwhich may be made of aluminum, 9 percent nickel steel or any othersuitable material. As shown in FIG. 5, at the lower end of the innersurface of each of the bearing members 30 there is provided a lateralbearing block 32, which is made of wood, laminated phenolic (micarta) orany other suitable material and has an outer contact bearing surface 33.At the bottom of each of the vertical bearing members 30 there issecured a contact bearing surface 34 made ofa material such as micarta,stainless steel, or the like, to vertically provide support for the tankIt) and any cargo contained therein. To the inner bottom of the tankerand disposed for alignment with the foregoing keyway-bearer means 28there are provided a pair of keywaybearer support means 28', comprisinga pair of laterally spaced elongated hollow keyway support stools 35,which comprise preferably 9 percent nickel steel or some other suitablematerial such as aluminum, etc. At the top or upper surface of each ofthe support stools 35 there is secured vertical contact bearing surfaces36, which are similar to the bearing surfaces 34 described heretofore.The support stools 35 are properly secured in place adjacent the innerbottom of the tanker by means of support brackets 37, which are similarto the support brackets 31 for the bearer members 30. The support stools35 are disposed such that when the tank 10 is mounted in the tankerscargo hold I5 the bearing surfaces 36 of the stools 35 will align incontact with the corresponding bearing surfaces 34 of the verticalbearing member 30. On the inner surface at the upper end and extendingthe length of the support stools 35 there are provided a pair ofopposing lateral bearing blocks 38, having outer contact surfaces 39,which are similar to the lateral bearing members 32. The spacing betweenthe lateral bearing blocks 38-38, as illustrated in FIG. 5, defines anelongated channel or keyway 40 having a width that is slightly smallerthan that between the lateral bearing blocks 3232 for reasons to bedescribed hereinafter. Also, disposed adjacent the inner bottom of thetanker are a pair of spaced support blocks 41 of suitable wood materialwhich are located between opposing inner faces of the support stools 35inwardly of the lateral contact surfaces 39. These blocks dl providevertical support for elongated hollow steel key 32 having a rectangularend cross section and which is to be slidably inserted into the channelformed by the keyways 29 and d ll upon mounting the tank It) in thetankers cargo hold M. Once the tank has been mounted with its bearermembers 30 properly located relative to the support stools 35, as shownin FIG. 5, the loose key 42, made preferably of fabricated steel, isfitted into each of the channels thereby to secure the tank from lateraland longitudinal movement relative to the tank top. The spacing betweenlateral bearing blocks -38 is such as to provide a relatively close fitfor the key 42. However, the keyway width defined between the lateralbearing blocks 32-32 secured to the tank It) is such that it is widerthan the corresponding key width at ambient temperature by an amountcarefully calculated to correspond to the thermal contraction when thetank MI is cooled to the temperature of the cryogenic cargo. Thus, whenthe tank lltl is at operating temperature the key 42 will fit neatly inthe keyway 29 defined between lateral bearing blocks 32-32. In additionto the foregoing described combined bearing-support arrangements locatedat each of the keykeyway means 28, the tank llll further is supportedvertically by additional bearing members 43 (similar to bearing members3d) and support pedestals M (similar to support stools 35) which extendlongitudinally near the outboard sides of the tank, as best illustratedin FIG. 2. Each of the bearing members $3 is suitably secured to theunderside of the tank 10 and is provided with a contact bearing surface45 that is similar to the bearing surfaced 3d, and each of the supportstools or pedestals MI is provided with a contact bearing surface aswhich is similar to the bearing surfaces 36. As shown in FIG. 6, it isclearly apparent that by using an arrangement including a loose key d2,that is, one structurally separate from the surrounding keyway defin ingstructure, the installation and repair of the keys and/or the keyways isgreatly simplified. A modification of the foregoing describedconstruction and arrangement that is within the scope of this inventionmay include making the bottom keys 4). in multiple lengths so thatcomplete withdrawal thereof for purposes of inspection or otherwise ispermitted. Thus, in the event of pitching or rolling movement of thetanker, the longitudinal and transverse key-keyway combinations properlywill secure the tank in place in the cargo hold while permitting thermalexpansion and contraction.

The tank 110 further is secured from undesirable movement by means ofthe longitudinal extending top key-keyway means 47 (secured to the tank)and 47' (secured to the deck 49) which comprise the system 26. The topor deck keyway 47 comprises a pair of laterally spaced support stools orpedestals dill fastened adjacent the underside of the deck 49. Eachinner surface of the support stools lltl at its bottom end is providedwith a lateral bearing block 50 having an outer bearing con tact surface5ll, similar to the lateral bearing blocks 32 and 38. The stools 45 aresecured to the underside of the deck 49 by means of metal supportbrackets 52 in a manner similar to that for the lower bearing andsupport members. The bearing blocks 50 define elongated channels orkeyways 53. The keyways 53 may be located in alternate bays (see FIG. 3)formed between the downward extending transverse deck girders 54 so asto facilitate insertion and removal of the keys d2 therefrom. This isbest illustrated in FIG. 3, wherein the key is shown in dotted linesprior to insertion into its keyway. At the top of the tank Ml there issecured the matching keyway 47 comprising a second pair of supportstools 55 which are held in spaced relation by means of support brackets56. A lateral bearing member 57 having a bearing contact surface 58 issecured to the inner surface at the upper end of each of the supportstools 55. These members 55 extend longitudinally the length of thestools and define an upper tank keyway 59. Located and secured to thetank top wall between the opposing inner faces of the support stools 55inwardly of the bearing members 57 are a pair of spaced support blocksas, preferably of a wood material, which function in a manner similar tothe support blocks 4111. As with the lower tank keyways 29, the top tankkeyway 59 is constructed to suit the dimension of the key 12 when thetank lltl is cold. Thus, as shown in FIG. 4, the spacing betweenthelateral bearing blocks 50 is less than the width between the lateralbearing members 57 so that when the key l2 slidably is inserted intoregister with the keyways 53 and 59 and the tank is cooled, the spacebetween the upper tank bearing members 57 will contract laterally withcorresponding contraction of the tank thereby to form a neat fit for theloose key 12. It is to be noted that when using a construction where thegirders extend down, the keys 42 are shorter than the distance betweenadjacent deck girders 54 so that installation is made easier. It isapparent from the foregoing description that installation of the tanks,deck structure and keyways can be completed before final fitting andinser tion of the keys into their corresponding keyways.

As an alternate arrangement to the above, both the top and bottom tankkeyways may be recessed into the tank structure (that is, the top andbottom tank walls), thereby permitting an increase in the size of thetanks relative to their capacity.

Further numerous alterations of the structure herein disclosed willsuggest themselves to those skilled in the art. How ever, it is to beunderstood that the present disclosure relates to a preferred embodimentof my invention which is for purpose of illustration only and is not tobe construed as a limita tion of the invention. All such modificationswhich do not depart from the spirit of the invention are intended to beincluded within the scope of the appended claims.

Having thus set forth the nature of the invention, what I claim hereinis:

H. In the storage and transportation of a material having a temperaturediffering widely from ambient temperature, a container of large capacityformed of a material characterized by substantial expansion andcontraction due to temperature changes and which has a substantiallyflat bottom, a supporting structure having a relatively flat floor,means for mounting said container within said supporting structure sothat said flat bottom is disposed in spaced relation relative to saidflat floor and in a manner to substantially stabilize the position ofsaid container within said supporting structure while permitting freeexpansion and contraction thereof, said mounting means comprising afirst and second plurality of longitudinally and transversely arrangedelongated keyways provided on said flat bottom of said container and onesaid "flat floor respectively, corresponding ones of said keyways ofsaid first and second plurality being disposed in vertically alignedmatched relation thereby to define a composite channel, an elongated keybeing slidably received in both of the keyways of each of said compositechannels, whereby said container is stabilized against any undesirablemovement relative to said supporting structure.

2. An assembly according to claim ll wherein the width of said firstplurality of keyways is greater than that of said second plurality ofkeyways by a predetermined amount corresponding to the amount ofcontraction of said container caused by the change from ambienttemperature to storage temperature.

3. An assembly according to claim ll wherein bearing means are operablyassociated with each of said keyways of said first and second pluralitywhereby said bearing means assists in maintaining said container in astabilized position.

t. An assembly according to claim 3 wherein said bearing means for eachof said keyways comprises a pair of laterally spaced horizontal bearingsurfaces located on opposite sides of said keyway, wherein said bearingsurfaces of said corresponding ones of said keyways are disposed incontact with each other.

5. An assembly according to claim 3 wherein said bearing means for eachof said keyways comprises a pair of opposing bearing members extendinglaterally inward of each of said keyways for contact with said key.

is. An assembly according to claim 3 wherein additional bearing meansare provided adjacent the periphery of said flat bottom of saidcontainer and support means for said bearing means are provided on saidflat floor for further supporting said container within said supportingstructure.

7. An assembly according to claim I wherein said container includes arelatively fiat top portion and said supporting structure has a topwall, a third and forth plurality of longitudinally arranged elongatedkeyways provided on said flat top portion and on said top wall,respectively, corresponding ones of said keyways of said third andfourth plurality being disposed in vertically aligned matched relation.

8. An assembly according to claim 7 wherein the width of said keywayscomprising said first and third plurality is greater than that of saidkeyways comprising said second and fourth plurality by a predeterminedamount corresponding to the amount of contraction of said containercaused by a change from ambient temperature to storage temperature.

9. An assembly according to claim 7 wherein bearing means are operablyassociated with said third and fourth plurality of said bearing meanscomprising a pair of opposing bearing members extending laterally inwardof each of said keyways disposed for contact with said key.

10. In the storage and transportation in the cargo hold of a tanker of amaterial having a temperature differing widely from ambient temperature,a tank of large capacity formed of a material characterized bysubstantial expansion and contraction due to temperature changes, saidtank having top and bottom walls, said cargo hold having a deck and afloor, means for securing said tank within said cargo hold so that saidbottom wall is spaced from said floor, said securing means comprising afirst and second plurality of opposing longitudinal and transversekeyways operably secured to said bottom wall and said floorrespectively, a third and fourth plurality of opposing longitudinalkeyways operably secured to said top and said deck respectively, keymeans separate from said keyways being slidably and removably disposedin opposing ones of said keyways thereby to stabilize and effectivelyisolate said tank from any movement transmitted by said tanker.

11. In the assembly of claim 10 wherein girders extend downward fromsaid deck in a transversely spaced arrangement thereby to define aplurality of bays, said fourth plurality of keyways being secured tosaid deck in alternate bays between said girders, thereby to facilitateinsertion of said key means into its corresponding keyways.

12. A tank of relatively large capacity for use in the storage andtransportation of material having a temperature differing widely fromambient temperature and being formed of a material characterized bysubstantial expansion and contrac tion caused by temperature changes,said tank being adapted for securement within a cargo containingstructure and having top, bottom and sidewalls, means adapted tosecurely position said tank within said enclosed area, said meanscomprising a first plurality of longitudinal and transverse extendingelongated channels formed on said bottom of said tank and a secondplurality of longitudinal extending elongated channels formed on saidtop of said tank, each of said channels being adapted to match with anopposing channel formed with the cargo containing structure thereby toform a composite keyway capable of slidably receiving a slidable andremovable key, whereby said tank will be secured in position when placedwithin said cargo containing structure.

1. In the storage and transportation of a material having a temperaturediffering widely from ambient temperature, a container of large capacityformed of a material characterized by substantial expansion andcontraction due to temperature changes and which has a substantiallyflat bottom, a supporting structure having a relatively flat floor,means for mounting said container within said supporting structure sothat said flat bottom is disposed in spaced relation relative to saidflat floor and in a manner to substantially stabilize the position ofsaid container within said supporting structure while permitting freeexpansion and contraction thereof, said mounting means comprising afirst and second plurality of longitudinally and transversely arrangedelongated keyways provided on said flat bottom of said container and onesaid flat floor respectively, corresponding ones of said keyways of saidfirst and second plurality being disposed in vertically aligned matchedrelation thereby to define a composite channel, an elongated key beingslidably received in both of the keyways of each of said compositechannels, whereby said container is stabilized against any undesirablemovement relative to said supporting structure.
 2. An assembly accordingto claim 1 wherein the width of said first plurality of keyways isgreater than that of said second plurality of keyways by a predeterminedamount corresponding to the amount of contraction of said containercaused by the change from ambient temperature to storage temperature. 3.An assembly according to claim 1 wherein bearing means are operablyassociated with each of said keyways of said first and second pluralitywhereby said bearing means assists in maintaining said container in astabilized position.
 4. An assembly according to claim 3 wherein saidbearing means for each of said keyways comprises a pair of laterallyspaced horizontal bearing surfaces located on opposite sides of saidkeyway, wherein said bearing surfaces of said corresponding ones of saidkeyways are disposed in contact with each other.
 5. An assemblyaccording to claim 3 wherein said bearing means for each of said keywayscomprises a pair of opposing bearing members extending laterally inwardof each of said keyways for contact with said key.
 6. An assemblyaccording to claim 3 wherein additional bearing means are providedadjacent the periphery of said flat bottom of said container and supportmeans for said bearing means are provided on said flat floor for furthersupporting said container within said supporting structure.
 7. Anassembly according to claim 1 wherein said container includes arelatively flat top portion and said supporting structure has a topwall, a third and forth plurality of longitudinally arranged elongatedkeyways provided on said flat top portion and on said top wall,respectively, corresponding ones of said keyways of said third andfourth plurality being disposed in vertically aligned matched relation.8. An assembly according to claim 7 wherein the width of said keywayscomprising said first and third plurality is greater than that of saidkeyways comprising said second and fourth plurality by a predeterminedamount corresponding to the amount of contraction of said containercaused by a change from ambient temperature to storage temperature. 9.An assembly according to claim 7 wherein bearing means are operablyassociated with said third and fourth plurality of said bearing meanscomprising a pair of opposing bearing members extending laterally inwardof each of said keyways disposed for contact with said key.
 10. In thestorage and transportation in the cargo hold of a tanker of a materialhaving a temperature differing widely from ambient temperature, a tankof large capacity formed of a material characterized by substantialexpansion and contraction due to temperature changes, said tank havingtop and bottom walls, said cargo hold having a deck and a fLoor, meansfor securing said tank within said cargo hold so that said bottom wallis spaced from said floor, said securing means comprising a first andsecond plurality of opposing longitudinal and transverse keywaysoperably secured to said bottom wall and said floor respectively, athird and fourth plurality of opposing longitudinal keyways operablysecured to said top and said deck respectively, key means separate fromsaid keyways being slidably and removably disposed in opposing ones ofsaid keyways thereby to stabilize and effectively isolate said tank fromany movement transmitted by said tanker.
 11. In the assembly of claim 10wherein girders extend downward from said deck in a transversely spacedarrangement thereby to define a plurality of bays, said fourth pluralityof keyways being secured to said deck in alternate bays between saidgirders, thereby to facilitate insertion of said key means into itscorresponding keyways.
 12. A tank of relatively large capacity for usein the storage and transportation of material having a temperaturediffering widely from ambient temperature and being formed of a materialcharacterized by substantial expansion and contraction caused bytemperature changes, said tank being adapted for securement within acargo containing structure and having top, bottom and sidewalls, meansadapted to securely position said tank within said enclosed area, saidmeans comprising a first plurality of longitudinal and transverseextending elongated channels formed on said bottom of said tank and asecond plurality of longitudinal extending elongated channels formed onsaid top of said tank, each of said channels being adapted to match withan opposing channel formed with the cargo containing structure therebyto form a composite keyway capable of slidably receiving a slidable andremovable key, whereby said tank will be secured in position when placedwithin said cargo containing structure.